The present invention relates generally to the field of alternating current (xe2x80x9cACxe2x80x9d) network interconnections, electricity generation and usage, and more particularly, to an electricity transfer station.
Electricity suppliers have traditionally sold electricity to large customers, such as large commercial and industrial customers, rural electric cooperatives and municipalities, based on a demand charge and the customer""s actual electricity usage. The demand charge is based on the customer""s expected or actual peak demand (normally measured in kilowatts (xe2x80x9cKWxe2x80x9d)) over a short period of time (normally 15 to 30 minutes) during a contractual billing period. The customer""s peak demand and electricity usage (normally measured in kilowatt-hours (xe2x80x9cKWHxe2x80x9d)) charges are typically specified in long term contracts. As a result, the customer pays a periodic fee, usually monthly, for the ability to draw its peak demand from the electricity supplier via a transmission network even though that peak demand may only occur once during the contractual billing period, if at all. Moreover, if the customer""s actual demand exceeds the contractual demand, significant excess demand charges and/or penalties may be imposed on the customer.
Some customers, such as rural electric cooperatives and municipalities, have negotiated long term, low cost electricity purchase contracts with their electricity suppliers. As the re-delivery market for electricity has developed over the years through deregulation and diversification, some of these customers and third-party electricity suppliers have seen an opportunity to purchase additional electricity under existing electricity purchase contracts and re-deliver that additional electricity to other customers at a profit. The sale of such additional electricity is, however, limited and reduced in value if it cannot be sold on a firm basis. For example, the customer may limit the amount of electricity that can be re-delivered based on the economics of the electricity purchase contract. Furthermore, the additional electricity may be reduced in value because it is sold under an interruptible contract, which means that the availability of the additional electricity is not guaranteed during peak demand periods. In order to provide non-interruptible electricity, the customer or third-party electricity supplier would risk setting a new peak demand for the customer, which may be financially unacceptable.
Accordingly, there is a need for an electricity transfer station that can provide an un-interruptible electricity supply for re-delivery to other electricity customers.
The present invention provides an electricity transfer station and a method of operating the electricity transfer station that allows electricity to be secured by a customer of an electricity supplier via a transmission network under an existing electricity supply contract and re-delivered by that customer to another party under a non-interruptible supply contract without risk of increasing the customer""s peak demand above a desired value. This system and method affords the customer more flexibility, and thus more opportunity to extract value from its supply contracts as well as its distribution, transmission and generation equipment.
More specifically, the present invention provides a method for providing a first electricity flow at a first network connection by monitoring a second electricity flow from a second network connection to one or more third network connections and one or more electricity transfer devices. The present invention then controls the one or more electricity transfer devices and one or more electricity sources so that the second electricity flow is less than or equal to a first value and the first electricity flow is provided at the first network connection.
The present invention also provides a method for providing a first electricity flow at an electricity re-delivery point by monitoring a second electricity flow at an electricity delivery point, monitoring the first electricity flow at the electricity re-delivery point, and monitoring an electricity transfer at one or more electricity transfer devices. The present invention then controls the one or more electricity transfer devices connected between the electricity delivery point and the electricity re-delivery point so that the second electricity flow is less than or substantially equal to a first value and the first electricity flow is substantially equal to a second value. In addition, the present invention controls one or more electricity sources connected to the electricity re-delivery point so that when the electricity transfer is substantially equal to the second value, the one or more electricity sources do not operate, and when the electricity transfer is less than the second value, the one or more electricity sources provide sufficient electricity flow such that the first electricity flow is substantially equal to the second value.
In addition, the present invention provides a system for providing a first electricity flow at a first network connection using a second electricity flow at a second network connection. The system includes one or more electricity transfer devices connected between the first network connection and the second network connection, one or more electricity sources connected to the first network connection, and an electricity transfer controller connected to the one or more electricity transfer devices, the one or more electricity sources, the first network connection and the second network connection. The electricity transfer controller monitors the first electricity flow and the second electricity flow, and controls the one or more electricity transfer devices and the one or more electricity sources so that the second electricity flow is less than or equal to a first value and the first electricity flow is provided at the first network connection.